Free Critical Thinking Skills

When I was younger, I often found myself disagreeing with something I’d read or heard, but couldn't explain exactly why. Despite being unable to pinpoint the precise reasons, I had a strong sense that the rules of logic were being violated. After I was exposed to critical thinking in high school and university, I learned to recognize problematic arguments, whether they be a straw man, an appeal to authority, or an ad hominem attack. Faulty arguments are all-pervasive, and the mental biases that underlie them pop up in media coverage, college classes, and armchair theorizing. Want to learn how to avoid them? Look no further than Critical Reasoning For Beginners, the top rated iTunesU collection of lectures led by Oxford University’s Marianne Talbot.

Talbot builds the course from the ground up, and begins by explaining that arguments consist of a set of premises that, logically linked together, lead to a conclusion. She proceeds to outline the way to lay out an argument logically and clearly, and eventually, the basic steps involved in assessing its strengths and weaknesses. The six-part series, which was recorded in 2009, shows no sign of wear, and Talbot, unlike some philosophy professors, does a terrific job of making the content digestible. If you’ve got some time on your hands, the lectures, which average just over an hour in length, can be finished in less than a week. That's peanuts, if you consider that all our knowledge is built on the foundations that this course establishes. If you haven’t had the chance to be exposed to a class on critical thought, I can’t recommend Critical Reasoning For Beginners with enough enthusiasm: there are few mental skills that are as underappreciated, and as central to our daily lives, as critical thinking.

Critical Reasoning For Beginners is currently available on the University of Oxford website in both audio and video formats, and also on iTunesU and YouTube. You can find it listed in our collection of Free Online Philosophy Courses, part of our collection of 1100 Free Online Courses.

Ilia Blinderman is a Montreal-based culture and science writer. Follow him at @iliablinderman, or read more of his writing at the Huffington Post.

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1) You have only an 8-liter jug and a 3-liter jug. Both containers are unmarked. You need exactly 4 liters of water.

How can you get it, if a water faucet is handy?

Question from Classroom Quickies • Show/Hide Solution

Answer: Fill the 3-liter jug three times, each time dumping the water from it into the 8-liter jug. The third time, this will leave one liter of water in the 3-liter jug, and the 8-liter jug will be filled. Dump the water from the 8-liter jug down the drain, and then empty the one liter of water from the 3-liter jug into the 8-liter jug. Now fill the 3-liter jug again and dump the water into the 8-liter jug. The 8-liter jug now contains 4 liters of water. Various answers are possible.

2) What can you add to 1,000,000 and always get more than if you multiplied the 1,000,000 by the same value?

Question from Scratch Your Brain • Show/Hide Solution

Answer: zero, any number less than and including 1.000001, any fraction less than a whole, or any negative number.

3) Determine the common saying depicted in these verbal picture puzzles.

a. DECI SION b. ANOTHER ONE

Question from Think-A-Grams • Show/Hide Solution

Answer: a. split decision; b. one after another

4) What is the 50th number in this sequence?

Explain how you got your answer. 5, 11, 17, 23, 29, 35, 41, …

Question from Dr. Funster’s Think-A-Minutes • Show/Hide Solution

Answer: 299. The pattern involves a difference of 6 between adjacent terms of the sequence. Add 6 to 5, getting 11, then add 6 to 11, getting 17, then add 6 to 17, getting 23, etc., until 6 has been added 50 times, ending in 299. Answer explanations will vary.

5) Determine both one-word answers.

The floor of ship or boat, They walk on me at sea; Where there’s a C, make it an S, At school you sit on me.

What am I? _______________

Question from Spelling DooRiddles • Show/Hide Solution

Answer: Deck, desk

6) The reason he gave the press for leaving his job was illness and fatigue. That wasn’t exactly the truth and it wasn’t exactly a lie.

Why did he leave?

Question from Red Herring Mysteries • Show/Hide Solution

Answer: He was the coach of a professional ball team. The teams owner fired him because he was sick and tired of the teams dismal performance. NOTE: Other explanations are accepted. Per the rules explained in the book one person is supposed to know the actual answer and the player(s) must ask "yes" or "no" questions to deduce the answer. This sample question is simply a fun way to practice critical and creative thinking.

7) Determine both one-word answers.

Another word for sick, Your forehead is quite hot; Now put an H in front, A mountain I am not.

What am I?______________

Question from Spelling DooRiddles • Show/Hide Solution

Answer: a. ill; b. hill

8) Use the clues to solve the puzzle.

A duck, a goose, a goat, and a horse all entered the barn at different times one day last week. a. A mammal entered the barn first. b. The duck entered before the goose. c. The goose entered ahead of the horse.

11) While relaxing on the deck outside her cabin one summer evening, Vivian fell into a deep trance-like sleep. When she awoke, she felt as if she had slept only an hour or two, but it was now the middle of winter.

How could this be?

Question from Red Herring Mysteries • Show/Hide Solution

Answer: Vivian was on the patio of her first class cabin on a cruise ship. She fell asleep just before the ship crossed the equator on a trip from Hawaii to New Zealand. The equator is the dividing line between the opposite seasons. She fell asleep north of the equator while in the middle of summer and awoke two hours later south of the equator in the middle of winter. NOTE: Other explanations are accepted. Per the rules explained in the book one person is supposed to know the actual answer and the player(s) must ask "yes" or "no" questions to deduce the answer. This sample question is simply a fun way to practice critical and creative thinking.

12) What do you get when a math teacher is a magician? ________________

Question from Scratch Your Brain • Show/Hide Solution

Answer: Tricky Problems

Answers to Questions: 1) Fill the 3-liter jug three times, each time dumping the water from it into the 8-liter jug. The third time, this will leave one liter of water in the 3-liter jug, and the 8-liter jug will be filled. Dump the water from the 8-liter jug down the drain, and then empty the one liter of water from the 3-liter jug into the 8-liter jug. Now fill the 3-liter jug again and dump the water into the 8-liter jug. The 8-liter jug now contains 4 liters of water. Various answers are possible.

2) zero, or any fraction less than a whole, or any negative number

3) a. split decision; b. one after another

4) 299. The pattern involves a difference of 6 between adjacent terms of the sequence. Add 6 to 5, getting 11, then add 6 to 11, getting 17, then add 6 to 17, getting 23, etc., until 6 has been added 50 times, ending in 299. Answer explanations will vary.

5) Deck, desk

6) He was the coach of a professional ball team. The team’s owner fired him because he was “sick and tired” of the team’s dismal performance.

11) Vivian was on the patio of her first class cabin on a cruise ship. She fell asleep just before the ship crossed the equator on a trip from Hawaii to New Zealand. The equator is the dividing line between the opposite seasons. She fell asleep north of the equator while in the middle of summer and awoke two hours later south of th equator in the middle of winter.

12) Tricky Problems

The Free Critical Thinking Quizzes are promotional quizzes, not be confused with our time tested and academically sound Cornell Critical Thinking Tests.